Do servos make noise while holding a position?

[allanonmage offline]

Hi there! New to robotics and I'm a little perplexed about something. I've gotten my Robophilo kit assembled and finally got a new board to make it work and I've noticed that when on, there's a buzzing sound coming from 1 or more of the servos. Is that normal? The servos make a similar noise if I try to push them out of their correct position, but I am unable tomake the general buzzing stop unless I turn off the controller. I've pushed on the servos and the servos groan and its ind of like. that.

I've made a youtube vid to highlight this: https://www.youtube.com/watch?v=LqDaola2GvQ

I'd have posted to the Robophilo forum, but that forum seems dead and I think this is more of a general question anyways.

I'm also concerned about the amount of play and wiggle in the servos. Towards the end of the video you can see the bot sway back and forth. Is that normal?

[limor]

all RC style servos make some kind of audiable noise

the reason is that the motor holds position by vibrating back and forth very quickly (1000 times per second). So visualize this little thing banging 1000 times per second against the gears. humans hear things that bang 20-20000 times per second.
it is possible to reduce audible noise by setting some parameters of the servo controller or using better motors or better gears in the servos.

[allanonmage offline]

Thanks for the reply! I'm not 100% clear; based on what you said, the noise amd wobble seem normal. If thats the case I'll try to tweak it but otherwise won't worry about it.

So what you are saying is that this level of noise and wobble is to be expected in these circumstances?

[serithseraki offline]

Yes, most servos will give some noise in one way or another. Depending on if the gears are nylon, karbonite, steel, or titanium "I think the Robophilo has nylon" the noise will be different. The motors, in order to hold their position have to cycle back and forth, this is done so fast that you can't really notice the slight motion, but depending on the power of the motor there will be slight twitches if a heavy load is bearing on the servo. Since the Robophilo is a very low cost kit, don't expect much power from it. I recommend you alter the Robophilo's standing pose to give it better balance and you may hear a slight difference in sound.